Asteroid to narrowly miss Earth on Tuesday

NASA scientists are tracking an asteroid bigger than an aircraft carrier that will fly by between the Earth and moon Tuesday. (NASA)

November 6, 2011 12:00:00 AM PDT

LOS ANGELES --

NASA scientists are tracking an asteroid bigger than an aircraft carrier that will fly by between the Earth and moon Tuesday.

Scientists say it will be our closest encounter with such a huge rock in 35 years. It will dart past Earth slightly closer than our moon's orbit. But scientists say not to worry. It won't hit us.

"We're extremely confident - 100 percent confident - that this is not a threat," said the manager of NASA's Near Earth Object Program, Don Yeomans.

The asteroid named 2005 YU55, which stretches a quarter-mile across, is being watched by ground antennas as it approaches from the direction of the sun.

Closest approach will occur at 3:28 p.m. PST when the asteroid passes within 202,000 miles of our planet.

The moon will be just under 150,000 miles from the asteroid at the time of closest approach.

Scientists have been tracking the slowly spinning, spherical, dark-colored object since they discovered it in 2005.

"We know the orbit of this object very well," Yeomans said.

Both the Earth and moon are safe - "this time," said Jay Melosh, professor of Earth and atmospheric sciences at Purdue University.

But if 2005 YU55 were to plow into the home planet, it would blast out a crater four miles across and 1,700 feet deep, according to Melosh's calculations. Think a magnitude-7 earthquake and 70-foot-high tsunami waves.

Smaller objects come close often, Yeomans noted, but nothing this big has come so close since 1976. And nothing this large will again until 2028.